Even though they state "Page Last Updated: 04/01/2010" at the bottom, they were only recently posted. These links should work "forever" (yeah, right!) - they are the same links I have been using for a few years now. I just noticed they were updated from 04/01/2009 to 04/01/2010.

As far as I know, figuring out what has changed is somewhat painful. You would have to go through each one, looking for citations. For example, if you look at the bottom of the 21 CFR 820.198 "Complaint files" page you will see this:
[61 FR 52654, Oct. 7, 1996, as amended at 69 FR 11313, Mar. 10, 2004; 71 FR 16228, Mar. 31, 2006]

If anyone knows of an easier way to determine changes, please let me know.